As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW RECEIVED A CABIN PRESS MASTER WARNING. CABIN SHOWED ABOVE 10000 FT, CREW DONNED O2 MASKS AND STARTED EMERGENCY DECENT TO 14,000 FT. CREW DECLARED AN EMERGENCY AND STARTED RETURN TO DEPARTURE. CREW RAN QRH FOR CABIN PRESS WHICH CLEARED THE FAULT INDICATION AND CABIN PRESSURE RETURNED TO NORMAL. ACFT LANDED WITHOUT INCIDENT. MX FOUND THE OUTFLOW VALVE HAD FAILED AND R & R IAW AMM. OPS CHECKED GOOD AND ACFT IS GOOD FOR SERVICE.